1. Field of the Disclosure
The present disclosure relates to an apparatus, arrangement and method for balancing a rotor disk in a gas turbine engine by adding balancing weights.
2. Description of the Related Art
Rotating components in gas turbine engines must be finely balanced so that the rotational axis of the component defined by the supporting bearings matches the centre of gravity and principal inertia axis of the component. Any mismatch between the two axes will result in an unbalance which may result in vibration and stresses within the gas turbine engine causing wear and damage to the supporting bearings.
A typical high pressure (HP) rotor in an aero-gas turbine engine requires balancing to within about 2 microns and it is necessary to ensure that this level of balancing can be achieved and maintained at all engine operating temperatures and speeds.
The various individual components, e.g. compressor or turbine, making up a rotor are separately balanced before being assembled into the complete rotor. This minimises the amount of balancing required for the complete assembled rotor. Once assembled, the complete rotor can be finely balanced using small correction weights. This fine balancing using correction weights is difficult to achieve for the HP rotor and intermediate pressure (IP) rotor which are relatively inaccessible because they are surrounded by annular casings.
It is known from US 2006/0266114 to provide openings in the annular casings surrounding the HP rotor through which a guide tube can be inserted. A balancing screw is inserted through the guide tube into a threaded hole in an insert housed in a circumferential groove in the outer surface of the rotor disk, the circumferential grove also housing the root portions of the rotor blades. This is repeated at various locations about the circumferential groove to finely balance the rotor.
This known arrangement requires a time-consuming and awkward mating of the threads of the balancing screw and the hole in the insert. It also requires use of a guide tube and specially formed inserts which increase the manufacturing costs.